The present invention is in the field of powered screeds used in the process of leveling, smoothing and creating an improved exposed surface on freshly poured concrete, cement, soil and like materials. Although the present invention is utilized in connection with many materials, the embodiment shown and described herein is directed to concrete. The word concrete includes a mixture of cement, sand, aggregate and water combined in a favorable ratio to create a product useful in the construction of floors, roads, driveways, sidewalks and the like. Concrete also embodies a mixture combined and mixed to a proper consistency and in a state of cure prior to set-up or hardening.
In the process of pouring concrete for floors, sidewalks, highways and the like, the exposed surface must be developed to a finished texture as required by the work specifications. This may vary from a rough nonslip surface to a slick polished finish. This is achieved by a process known as screeding. This process brings a tool into contact with the surface of the poured concrete, and by a reciprocating, dragging action causes the aggregate near and at the surface to settle thereby leaving cement and water exposed while, at the same time, leveling and smoothing the exposed surface material.
In one screeding system, common to the industry, an elongated wood beam or screed of sufficient length is manipulated in a side-to-side sawing motion along pairs of supporting rails temporarily set at the desired finished elevation of the surface being poured. This side-to-side motion is combined with pressure against the beam to force travel along the supporting rails. In this system, all power is applied manually by workmen positioned at opposite ends of the beam.
On larger areas, such as highway lanes and large floors, the typical process utilizes a screed provided with means to mechanically power both the sawing motion and travel along the guiding rails with travel being implemented by powered traction wheels.
A third system, in current use in the industry, includes a screed beam, power means to effect side-to-side sawing motion, a guide with a controlling handle and a frame on which all of the elements are mounted. This system commonly utilizes one operator in the fashion of a push-type lawnmower with the operator causing the machine to travel by applying a push or pull force to the machine handle.